Bumping gaia.json for 2 gaia-central revision(s)

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https://hg.mozilla.org/integration/gaia-central/rev/d931331d83d7
Author: Arthur Chen <crh0716@gmail.com>
Desc: Merge pull request #11803 from crh0716/905969

Bug 905969 - Turn off vibration only when leaving the silent mode r=alive a=leo+

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https://hg.mozilla.org/integration/gaia-central/rev/755516f9a719
Author: Arthur Chen <crh0716@gmail.com>
Desc: Bug 905969 - Turn off vibration only when leaving the silent mode